There are a lot of lyric sites out there, but so many of them are plagued by overwhelming ads, garbage, and slow load times. Now that Bing has lyrics built-in to its search results, it's the place to go.
When you search lyrics on Bing, it will give you the lyrics right there in your results -- no need to wait for a trashy site to load. We're not sure what site they're using to pull the lyrics, and it doesn't work for every song -- I found that it didn't work for some more obscure bands -- but in those cases, you still have regular old lyrics sites in your results to fall back on. Hopefully it continues to improve, but for now we can count it as one more thing Bing actually does well.